Morning thunderstorms bring over 8000 lightning strikes

Friday, 17 August 2018

MetService National Forecast

More than 8000 lightning strikes hit the west coast of the North Island during Friday morning, MetService says.

Thunderstorms were forecast to hit the North Island before dawn, bringing heavy rain and hail, along with strong wind gusts which could produce one or two short-lived small tornados.

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In Auckland, heavy showers caused surface flooding in some areas, and Auckland Transport were urging people to drive with care.

BOND STREET OVER BRIDGE, GREY LYNN FLOODING - 9.30AM

Extra caution is advised on the Bond Street over-bridge due to surface water and flooding. Please avoid the area if possible or drive with care. ^MF pic.twitter.com/sdtQcfCf2U

— Auckland Transport (@AklTransport) August 16, 2018

A series of fronts and troughs are moving onto New Zealand from the Tasman Sea, bringing the turbulent weather to western areas.

The North Island was struck by lightning more than 8000 times as a storm moved up the west of the country. (File photo)

There is a risk the thunderstorms could turn severe as they move north from the Kāpiti Coast up to Taranaki before dawn and from Waitomo up to Northland, including the Hauraki Gulf during the morning.

Meanwhile, in the South Island, snowfall could make some alpine roads tricky to navigate - MetService issued road snowfall warnings for Porters Pass (SH73), Lindis Pass, Crown Range Rd and Milford Rd (SH94).

However, the roads should remain clear on other alpine roads and there are no road snowfall warnings for Napier-Taupo Road (SH5), Desert Road (SH1), Rimutaka Hill Road (SH2), Lewis Pass (SH7), Arthur's Pass (SH73), Haast Pass (SH6) and Dunedin to Waitati Highway (SH1).

Fiordland and southern Westland could also see thunderstorms before dawn, and Nelson during the morning. MetService says these thunderstorms could bring heavy rain with intensities of 5mm to 15mm per hour and small hail.

There is also a low risk of morning thunderstorms for Coromandel Peninsula and Bay of Plenty.

MetService meteorologist Tui McInnes said most of the strikes were out in the Tasman Sea, but about 3500 had hit closer to land since midnight.

A series of fronts are moving in from the Tasman Sea, bringing bursts of heavy rain and thunderstorms to western areas.

🌩🌩 Since midday there have been 8643 recorded lightning strikes 🌩🌩 in an active front moving across from the Tasman sea. You can see the rainfall on our rain radar https://t.co/prKU7O2R01

^Tui pic.twitter.com/P00eZmbO1R

— MetService (@MetService) August 16, 2018

'The early morning was a great time of day for people to see them,' he said.

'As the storm moves east over New Zealand, the thunderstorm will lose strength because of the colder temperatures on land.'

Water is warmer than land at this time of day and as the storm moves away into the Pacific its intensity would increase again, McInnes said.

MetService had not yet received any reports of tornadoes, but there had been heavy bursts of rain in isolated areas.

'With systems like these, there can be heavy falls in one location, but only 20 kilometres away there can be almost nothing.'

Parts of Manawatū experienced downfalls in excess of 15 millimetres in an hour, McInnes said.

'The silver lining is the worst will be over soon, and behind that it's looking not too bad.'

Earlier, MetService warned heavy rainfall could trouble Buller and north-west Nelson, and also the Tararua Range, Mt Taranaki, Tongariro National Park and the hill country from Taranaki to Lake Taupo, including Waitomo and the headwaters of the Whanganui River.

MAIN CENTRES

In Auckland, periods of rain might dampen the morning and there is a chance of a thunderstorm, however conditions should ease by early afternoon. MetService forecasts a high of 16 degrees Celsius.

Similar conditions further south mean it could be a wet and thundery start to the day for Hamilton and Tauranga, easing after midday. The cities are forecast to reach 15C and 16C respectively.

A few showers for Wellington, mainly in the north, clear to produce a fine day, however showers could return in the evening - 14C is the high.

In Christchurch, cloud is forecast to increase throughout the morning while scattered rain could fall in the afternoon, with a high of 13C.

Showers and southerly winds develop in Dunedin during the morning, but should clear by the evening - a high of 10C is expected.